In electronics, current bias is a steady state current that is forced through an electronic device like a transistor, coil or other source of load. This is accomplished by varying the voltage across the device in order to fulfill the equation Electronics is the study and use of electrical devices that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. ... In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ... Through hole transistors (tape measure marked in centimeters) The transistor is a solid state semiconductor device which can be used for amplification, switching, voltage stabilization, signal modulation and many other functions. ... Load is what is carried, or a force. ... In the physical sciences, potential difference is the difference in potential between two points in a conservative vector field. ...
V = I * R
which relates the voltage (V) with the current (I) passing through a device and its resistance (R). Current bias can be "broken" if the load induces a voltage that cannot be maintained. Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...
Therefore, the operating point for the output (drain current and voltage) is set by ensuring that the voltage on the gate (or gates, in the case of dual-gate devices) is the correct voltage.
This current charges up the source bypass capacitor and eventually the current must stabilise with a DC flow through the source resistor that pulls the source voltage above reference ground, causing an equivalent reverse biasvoltage to appear between the gate and source, since the gate is connected to ground via a high-valued resistor.
The drain current characteristic curves on this plot (in blue) are a family of similar curves which start at zero drain voltage and current, increase in current rapidly up to a "knee" or "corner" and then level off with the drain current not increasing much as the drain voltage increases further.
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